The well-known Californian psychologist has spent more than 30 years writing about sexual issues, often attracting the blowtorch of indignation from the US's powerful conservative groups.

But he's never experienced anything like the frothing-at-the-mouth nastiness he's experienced since commenting on a recent controversy over an unwanted sexual invitation.

It started when a woman, Elyse Anders, was speaking at a sceptics' conference. She was approached by a couple she'd had contact with through Facebook who presented her with a SwingLifeStyle card that included their names, phone number and a semi-naked photo of them. They then left.

Anders posted a seething blog on her website, ranting about how offensive this was, how it undermined her professionalism.

''I do important work. The work I do saves lives. And yet I still have to worry about whether I'm worthy or if I'll ever be respected beyond my f***ability. And that's bullshit. I deserve better than that.''

In his regular column in Psychology Today, Klein took up the issue, perhaps foolishly disguising some details of the case to present a more general scenario.

But he made a powerful argument, suggesting the issue here isn't sexual harassment but rather unwanted sexual attention. He then described the legal, ethical and social differences between the two.

Klein argued that sexual-harassment law was never designed to protect women from merely feeling uncomfortable and that in a typical workday, for instance, both men and women face many sources of discomfort: the infertile face co-workers' desks with photos of their kids; fundamentalist Muslims and Jews face people dressed with arms and legs uncovered; atheists face people wearing crosses. Why do we privilege unwanted attention that happens to involve sexuality?

We all cope with unwanted attention every day, Klein said, coming up with some telling examples: overly personal stories from strangers on planes; awkward compliments from co-workers; grocery clerks sympathetically inquiring about the brace on your wrist; and ''Jehovah's Witnesses or Mormon missionaries asking if they can talk with you for just a moment about their invisible friend in the sky''.

Klein pointed out that he had fought hard against sexual coercion and sexual harassment but suggested the whole ''Eek! An unwanted sexual invitation - gross! My day/week/year is ruined'' is a bit precious. He concluded that surely we should be able to handle a friendly sexual invitation in a genuinely safe environment without losing our composure.

He makes a good point. It seems extraordinary that Anders got her knickers in a twist about simply being handed a piece of paper, with no pressure to make any further response.

Since Klein's article was published, Anders has responded with 5000 words of venomous blog, tearing him apart and nit-picking about his inaccuracies, but never discussing the important issues he raised. The article also led to hundreds of furious comments, blogs and threats to interfere with his regular writing assignments.

There's a very real issue at the heart of this silly controversy - namely, the notion that sex is peculiarly dangerous and the rules of normal adult interaction must be adjusted when the subject is sex so no one ever feels uncomfortable.

Look at the constant skirmishes now taking place in workplaces, where the wrong joke, comment or sexual reference risks accusations of sexual harassment.

Yet, as even the feminist website ffeusa.org points out, there are women who make and enjoy sexual banter.

As this site suggests: ''Overbroad restrictions on sexual material infantilises women and shores up destructive Victorian stereotypes that women are (or should be) so pure that any expression about sexuality offends and demoralises them.''

Sexual banter, the exchange of jokes and flirty comments can be the welcome spice of life for women, as well as men, and it's foolish to let the prudish in our midst determine what is appropriate behaviour.

Demonising sexuality inevitably distorts a proper perspective on sexual crimes, leading to politically inspired calls for absurdly longer sentences, misinformation about the likelihood of offenders to reoffend and exaggeration of the emotional damage to the victims of minor abuse.

Our prurient interest in sex crimes often robs the perpetrator of any chance of redemption - as the sad death of cricket commentator Peter Roebuck bears witness. This is why allegations of child sexual abuse feature so regularly in fierce battles over child custody - the hint of sexual misbehaviour is a weapon like no other, leaving a lifelong taint on character.

The absurd overreaction from Anders and her colleagues to Klein's serious discussion of unwanted sexual attention makes the case that reason disappears when sex rears its head.

Bettina Arndt is a social commentator and author of What Men Want - In Bed.